okay, so I’ve looked at the code now, and while I don’t know exactly what’s happening on your end, I can explain what it is trying to do.
It tries to make a list of all of the influences on the selected geometry. Your error though is saying there is nothing in that list (NoneType is not iterable).
The whole code breaks down like this:
-find all skin clusters and find the geometry they belong to
-if geometry of skinCluster matches selection, get list of influences (yours is coming up empty)
-populate the UI with all of the joints
-remove joints from UI that are not in list of influences (this is where you error)
I would need to see your scene to debug this, but I don’t think the code is acting up here, I think there must be something odd about the file.
Some possible things to check would be history on your meshes, mesh names and their shape names, and making sure nothing in the scene has the same name as anything else.
Also, try using Maya’s paint weights and see what populates in the UI. That might give some clues as well.